In general, during rotation of a machine-worked product, a rotation shaft of a motor, or a main spindle of a machine tool, which has a cylindrical shape, there is generated a positional error, which corresponds to their displacement during rotation in X, Y, and Z axis directions, and an angular error, which corresponds to their tilting during rotation with respect to the X, Y, and Z axis directions, based on their normal positions.
In order to correct the positional error and angular error, a measurement of an error value should be done in advance through a measurement apparatus. In this respect, various types of apparatuses for measuring the positional error and angular error are conventionally disclosed.
However, there is no disclosed technology enabling one general measurement apparatus to measure 6 error components of the above described rotation driving shaft, i.e. both the positional error and the angular error with respect to each of the X, Y, and Z axis directions. Therefore, it has required selecting the measurement apparatus appropriate for the error type to be measured or using two or more measurement apparatuses if it is desired to measure every error component.
In this respect, it is essentially necessary to develop an apparatus for measuring a quasi-static error which can measure 6 error components by means of a single apparatus, thereby achieving an easy and prompt error measurement.